Mobile communication system and radio base station

ABSTRACT

A mobile communication system according to the present invention is configured such that a relay node RN is configured to time-share a subframe for transmission and reception in a Un interface and a subframe for transmission and reception in a Uu interface, and a radio base station DeNB is configured to transmit SI, which is to be transmitted in a subordinate cell, to the relay node RN via individual signaling.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of and, thereby,claims benefit under 35 U.S.C. §120 to U.S. patent application Ser. No.13/521,000 filed on Jul. 6, 2012, which is a national stage applicationof PCT Application No. PCT/JP2011/050184, filed on Jan. 7, 2011, whichclaims priority to Japanese Patent Application No. 2010-003381 filed onJan. 8, 2010. The content of these applications is incorporated byreference in their entirety.

TECHNICAL FIELD

The present invention relates to a mobile communication system and aradio base station.

BACKGROUND ART

In a mobile communication system employing an LTE (Long TermEvolution)-Advanced scheme for which the 3GPP is developing aspecification, the application of “L3 Relay (Type 1 Relay)” using arelay node RN has been discussed.

However, in a conventional mobile communication system, in order toguarantee a “Backward compatibility” for a mobile station UE in a cellsubordinate to a relay node RN (Relay Node), it is necessary for therelay node RN to time-share a subframe for transmission and reception ina Un interface and a subframe for transmission and reception in a Uuinterface, by using an MBSFN (MBMS over a Single Frequency Network)subframe.

Therefore, it is possible for the relay node RN to receive a downlinksignal from a radio base station DeNB (a Donor eNB) only in the MBSFNsubframe. Thus, there is a problem that when broadcast informationtransmitted by the radio base station DeNB has been changed, it is notpossible for the relay node RN to immediately receive the broadcastinformation.

SUMMARY OF THE INVENTION

Therefore, the present invention has been achieved in view of theabove-described problems, and an object thereof is to provide a mobilecommunication system and a radio base station, by which it is possiblefor a relay node to reliably receive broadcast information transmittedby a radio base station.

A first characteristic of the present embodiment is summarized in that amobile communication system, in which a radio base station and a relaynode are connectable to each other via a first interface, and in whichthe relay node and a mobile station are connectable to each other via asecond interface, in which the relay node is configured to time-share aperiod for transmission and reception in the first interface and aperiod for transmission and reception in the second interface, and theradio base station is configured to transmit broadcast information,which is to be transmitted in a subordinate cell, to the relay node viaindividual signaling.

A second characteristic of the present embodiment is summarized in thata radio base station in a mobile communication system, in which theradio base station and a relay node are connectable to each other via afirst interface, and in which the relay node and a mobile station areconnectable to each other via a second interface, comprising, abroadcast information transmission unit configured to transmit broadcastinformation in a subordinate cell, and an individual signaling unitconfigured to transmit the broadcast information to the relay node viaindividual signaling.

A third characteristic of the present embodiment is summarized in that amobile communication system, in which a radio base station and a relaynode are connectable to each other via a first interface, and in whichthe relay node and a mobile station are connectable to each other via asecond interface, in which the relay node is configured to time-share aperiod for transmission and reception in the first interface and aperiod for transmission and reception in the second interface, and theradio base station is configured to transmit identification informationfor a mobile station and a first scheduling signal via a physicaldownlink control channel, and to transmit broadcast information via abroadcast channel designated by the first scheduling signal, and theradio base station is configured to transmit identification informationfor a relay node and a second scheduling signal via the physicaldownlink control channel, and to transmit the broadcast information viaa broadcast channel designated by the second scheduling signal.

A fourth characteristic of the present embodiment is summarized in thata radio base station in a mobile communication system, in which theradio base station and a relay node are connectable to each other via afirst interface, and in which the relay node and a mobile station areconnectable to each other via a second interface, comprising, a mobilestation-use broadcast information transmission unit configured totransmit identification information for a mobile station and a firstscheduling signal via a physical downlink control channel, and totransmit broadcast information via a broadcast channel designated by thefirst scheduling signal, and a relay node-use broadcast informationtransmission unit configured to transmit identification information fora relay node and a second scheduling signal via the physical downlinkcontrol channel, and to transmit the broadcast information via abroadcast channel designated by the second scheduling signal.

A fifth characteristic of the present embodiment is summarized in that amobile communication system, in which a radio base station and a relaynode are connectable to each other via a first interface, and in whichthe relay node and a mobile station are connectable to each other via asecond interface, in which the relay node is configured to time-share aperiod for transmission and reception in the first interface and aperiod for transmission and reception in the second interface, and theradio base station is configured to transmit a first scheduling signalvia a physical downlink control channel, and to transmit broadcastinformation via a broadcast channel designated by the first schedulingsignal, and the radio base station is configured to transmit a secondscheduling signal via a physical downlink control channel dedicated to arelay node, and to transmit the broadcast information via a broadcastchannel designated by the second scheduling signal.

A sixth characteristic of the present embodiment is summarized in that aradio base station in a mobile communication system, in which the radiobase station and a relay node are connectable to each other via a firstinterface, and in which the relay node and a mobile station areconnectable to each other via a second interface, comprising, a mobilestation-use broadcast information transmission unit configured totransmit a first scheduling signal via a physical downlink controlchannel, and to transmit broadcast information via a broadcast channeldesignated by the first scheduling signal, and a relay node-usebroadcast information transmission unit configured to transmit a secondscheduling signal via a physical downlink control channel dedicated to arelay node, and to transmit the broadcast information via a broadcastchannel designated by the second scheduling signal.

As described above, according to the present invention, it is possibleto provide a mobile communication system and a radio base station, bywhich it is possible for a relay node to reliably receive broadcastinformation transmitted by a radio base station.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing the entire configuration of a mobilecommunication system according to a first embodiment of the presentinvention.

FIG. 2 is a functional block diagram of a relay node according to thefirst embodiment of the present invention.

FIG. 3 is a functional block diagram of a radio base station accordingto the first embodiment of the present invention.

FIG. 4 is a functional block diagram of a radio base station accordingto a second embodiment of the present invention.

FIG. 5 is a diagram explaining an adjustment method of a transmissiontiming of an uplink signal by a mobile station according to the secondembodiment of the present invention.

FIG. 6 is a diagram explaining an adjustment method of transmissiontiming of an uplink signal by the mobile station according to the secondembodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

(Mobile Communication System According to First Embodiment of thePresent Invention)

With reference to FIG. 1 to FIG. 3, a mobile communication systemaccording to a first embodiment of the present invention will bedescribed.

The mobile communication system according to the present embodiment isan LTE-Advanced mobile communication system, and includes a radio basestation DeNB, a relay node RN, and a plurality of mobile stations UE asillustrated in FIG. 1.

The radio base station DeNB and the relay node RN are configured to beconnected to each other through a Un interface, and the relay node RNand each mobile station UE are configured to be connected to each otherthrough a Uu interface.

As illustrated in FIG. 2, the relay node RN includes a reception unit 21and a transmission unit 22.

The reception unit 21 is configured to receive a signal from the radiobase station DeNB in a subframe for reception in the Un interface, and asignal from the mobile station UE in a subframe for reception in the Uuinterface.

In addition, as will be described later, the reception unit 21 isconfigured to receive SI (System Information), which is broadcastinformation transmitted in a cell subordinate to the radio base stationDeNB, via individual signaling from the radio base station DeNB.

The transmission unit 22 is configured to transmit a signal to the radiobase station DeNB in a subframe for transmission in the Un interface,and a signal to the mobile station UE in a subframe for transmission inthe Uu interface.

In the mobile communication system according to the present embodiment,the relay node RN is configured to time-share a subframe fortransmission and reception in the Un interface and a subframe fortransmission and reception in the Uu interface.

That is, in the Uu interface, the relay node RN is configured totransmit a signal to the mobile station UE only in an MBSFN subframe.

As illustrated in FIG. 3, the radio base station DeNB includes abroadcast information transmission unit 1 and an individual signalingunit 2.

The broadcast information transmission unit 1 is configured to transmitSI (System Information) such as MIB (Master Information Block) or SIB(System Information Block) in a subordinate cell.

Specifically, the broadcast information transmission unit 1 isconfigured to transmit BCCH (Broadcast Control Channel)-RNTI (RadioNetwork Temporary Identity) and a scheduling signal via PDCCH (PhysicalDownlink Control Channel), and to transmit the SI via BCCH transmittedby PDSCH (Physical Downlink Shared Channel) designated by the schedulingsignal.

The individual signaling unit 2 is configured to transmit the SI to therelay node RN via individual signaling.

Specifically, it is configured to transmit C-RNTI (may also be calledRN-RNTI because it is for the relay node RN) individually assigned tothe relay node RN and a scheduling signal via the PDCCH or RPDCCH whichwill be described later, and to transmit the SI via DCCH (DedicatedControl Channel: individual control channel) transmitted by PDSCHdesignated by the scheduling signal.

In accordance with the mobile communication system according to thefirst embodiment of the present invention, even when there are aplurality of relay nodes RN in which timings of MBSFN subframes aredifferent from one another, it is possible to reliably transmit the SIto each of the relay nodes RN via individual signaling.

(Mobile Communication System According to Second Embodiment of thePresent Invention)

With reference to FIG. 1, FIG. 4, and FIG. 5, the mobile communicationsystem according to a second embodiment of the present invention will bedescribed. Hereinafter, the following is a description of the mobilecommunication system according to the second embodiment of the presentinvention while focusing on the difference from the above-describedmobile communication system according to the first embodiment of thepresent invention.

As illustrated in FIG. 4, the radio base station DeNB includes a mobilestation-use SI transmission unit 11 and a relay node-use SI transmissionunit 12.

The mobile station-use SI transmission unit 11 is configured to transmitBCCH-RNTI and a scheduling signal via the PDCCH, and to transmit SI viaBCCH transmitted by PDSCH designated by the scheduling signal.

FIG. 5 illustrates timings of subframes for transmission in the radiobase station DeNB and timings of subframes for transmission in the relaynode RN.

In the mobile communication system according to the present embodiment,as illustrated in FIG. 5, the timings of the subframes for transmissionin the radio base station DeNB are shifted from the timings of thesubframes for transmission in the relay node RN by a predeterminednumber of (for example, one) symbols.

Here, the mobile station-use SI transmission unit 11, for example, isconfigured to transmit the BCCH-RNTI and the scheduling signal via thePDCCH in subframes #1, #3, and #4, and to transmit the SI via the BCCHmapped to the PDSCH (Physical Downlink Shared Channel) designated by thescheduling signal.

The relay node-use SI transmission unit 12 is configured to transmitRN-specific-BCCH-RNTI and a scheduling signal via the PDCCH, and totransmit the SI via BCCH mapped to PDSCH designated by the schedulingsignal.

Here, the relay node-use SI transmission unit 12, for example, isconfigured to transmit the RN-specific-BCCH-RNTI and the schedulingsignal via the PDCCH in a subframe #2 corresponding to a period (DTX) inwhich a signal is not transmitted in the relay node RN, and to transmitthe SI via the BCCH mapped to the PDSCH designated by the schedulingsignal.

Furthermore, the relay node-use SI transmission unit 12 may beconfigured to repeatedly transmit the aforementioned SI, periodically.Here, the relay node-use SI transmission unit 12 may be configured torepeatedly transmit the SI by a sufficient number of times inconsideration of the timing of an MBSFN subframe in each relay node RN,so that the SI is received in all relay nodes RN.

Moreover, the relay node-use SI transmission unit 12 may be configuredto transmit the SI, in addition to when the SI has been changed, byusing the aforementioned method.

In addition, as illustrated in FIG. 5, the mobile station-use SItransmission unit 11 is configured to transmit RS (Reference Signal)together with a PDCCH signal at one symbol of a head of a subframe #1.

Similarly, the relay node-use SI transmission unit 12 is configured totransmit the RS together with the PDCCH signal at one symbol of a headof a subframe #1A.

In accordance with the mobile communication system according to thesecond embodiment of the present invention, it is possible for themobile station UE to receive the SI using the BCCH-RNTI, and it ispossible for the relay node RN to receive the SI using theRN-specific-BCCH-RNTI as before.

Consequently, it is possible for the radio base station DeNB to transmitthe SI to a plurality of relay nodes RN without using individualsignaling.

(First Modification)

With reference to FIG. 6, a first modification of the mobilecommunication system according to the second embodiment of the presentinvention will be described. Hereinafter, the following is a descriptionof the mobile communication system according to the present firstmodification while focusing on the difference from the above-describedmobile communication system according to the second embodiment of thepresent invention.

In the mobile communication system according to the present firstmodification, as illustrated in FIG. 6, the timings of the subframes fortransmission in the radio base station DeNB coincide with the timings ofthe subframes for transmission in the relay node RN.

Furthermore, in the radio base station DeNB according to the presentfirst modification, similarly to in the radio base station DeNBaccording to the second embodiment of the present invention, the mobilestation-use SI transmission unit 11 is configured to transmit BCCH-RNTIand a scheduling signal via the PDCCH, and to transmit SI via BCCHmapped to PDSCH designated by the scheduling signal.

Here, the mobile station-use SI transmission unit 11, for example, isconfigured to transmit the BCCH-RNTI and the scheduling signal via thePDCCH in subframes #1, #3, and #4, and to transmit the SI via the BCCHmapped to the PDSCH designated by the scheduling signal.

Furthermore, in the radio base station DeNB according to the presentfirst modification, the relay node-use SI transmission unit 12 isconfigured to transmit a scheduling signal via the RPDCCH(RN-specific-PDCCH), and to transmit the SI via BCCH mapped to PDSCHdesignated by the scheduling signal.

The RPDCCH is PDCCH for the relay node RN and is a channel forperforming scheduling for the relay node RN. An RPDCCH signal is notreceived in the mobile station UE.

Here, the relay node-use SI transmission unit 12, for example, isconfigured to transmit the BCCH-RNTI (or the RN-specific-BCCH-RNTI) andthe scheduling signal via the RPDCCH in a subframe #2 corresponding to aperiod (DTX) in which a signal is not transmitted in the relay node RN,and to transmit the SI via the BCCH mapped to the PDSCH designated bythe scheduling signal.

In addition, as illustrated in FIG. 6, a resource for the RPDCCH isconfigured to be mapped to a symbol period equal to that of a resourcefor the PDSCH in the subframe #2.

In addition, in the above embodiments, the relay node-use SItransmission unit 12 may be configured to transmit only partial SIincluding only a parameter in which a change has occurred.

The characteristics of the present embodiment as described above may beexpressed as follows.

A first characteristic of the present embodiment is summarized in amobile communication system, in which a radio base station DeNB and arelay node RN are connectable to each other via a Un interface (a firstinterface), and in which the relay node RN and a mobile station UE areconnectable to each other via a Uu interface (a second interface), therelay node RN is configured to time-share a subframe (a period) fortransmission and reception in the Un interface and a subframe fortransmission and reception in the Uu interface, and the radio basestation DeNB is configured to transmit SI (broadcast information), whichis to be transmitted in a subordinate cell, to the relay node RN viaindividual signaling.

A second characteristic of the present embodiment is summarized in aradio base station DeNB in a mobile communication system, in which theradio base station DeNB and a relay node RN are connectable to eachother via a Un interface, and in which the relay node RN and a mobilestation UE are connectable to each other via a Uu interface, whichincludes: a broadcast information transmission unit 1 configured totransmit SI in a subordinate cell, and an individual signaling unit 2configured to transmit the SI to the relay node RN via individualsignaling.

A third characteristic of the present embodiment is summarized in amobile communication system, in which a radio base station DeNB and arelay node RN are connectable to each other via a Un interface, and inwhich the relay node RN and a mobile station UE are connectable to eachother via a Uu interface, the relay node RN is configured to time-sharea subframe for transmission and reception in the Un interface and asubframe for transmission and reception in the Uu interface, and theradio base station DeNB is configured to transmit BCCH-RNTI(identification information for a mobile station) and a first schedulingsignal via PDCCH (Physical Downlink Control Channel), to transmit SI(broadcast information) via BCCH (a broadcast channel) designated by thefirst scheduling signal, to transmit RN-specific-BCCH-RNTI(identification information for a relay node) and a second schedulingsignal via the PDCCH, and to transmit the SI via BCCH designated by thesecond scheduling signal.

A fourth characteristic of the present embodiment is summarized in aradio base station DeNB in a mobile communication system, in which theradio base station DeNB and a relay node RN are connectable to eachother via a Un interface, and in which the relay node RN and a mobilestation UE are connectable to each other via a Uu interface, whichincludes: a mobile station-use SI transmission unit 11 configured totransmit BCCH-RNTI and a first scheduling signal via PDCCH, and totransmit SI via BCCH designated by the first scheduling signal; and arelay node-use SI transmission unit 12 configured to transmitRN-specific-BCCH-RNTI and a second scheduling signal via the PDCCH, andto transmit the SI via BCCH designated by the second scheduling signal.

A fifth characteristic of the present embodiment is summarized in thatin a mobile communication system, in which a radio base station DeNB anda relay node RN are connectable to each other via a Un interface, and inwhich the relay node RN and a mobile station UE are connectable to eachother via a Uu interface, the relay node RN is configured to time-sharea subframe for transmission and reception in the Un interface and asubframe for transmission and reception in the Uu interface, and theradio base station DeNB is configured to transmit a first schedulingsignal via PDCCH, to transmit SI via BCCH designated by the firstscheduling signal, to transmit a second scheduling signal via RPDCCH(Physical Downlink Control Channel dedicated to a relay node), and totransmit the SI via BCCH designated by the second scheduling signal.

A sixth characteristic of the present embodiment is summarized in that aradio base station DeNB in a mobile communication system, in which theradio base station DeNB and a relay node RN are connectable to eachother via a Un interface, and in which the relay node RN and a mobilestation UE are connectable to each other via a Uu interface, includes: amobile station-use SI transmission unit 11 configured to transmit afirst scheduling signal via PDCCH, and to transmit SI via BCCHdesignated by the first scheduling signal; and a relay node-use SItransmission unit 12 configured to transmit a second scheduling signalvia RPDCCH, and to transmit the SI via BCCH designated by the secondscheduling signal.

It is noted that the operation of the above-described the mobile stationUE, the radio base station DeNB or the relay node RN may be implementedby a hardware, may also be implemented by a software module executed bya processor, and may further be implemented by the combination of theboth.

The software module may be arranged in a storage medium of an arbitraryformat such as RAM (Random Access Memory), a flash memory, ROM (ReadOnly Memory), EPROM (Erasable Programmable ROM), EEPROM (ElectronicallyErasable and Programmable ROM), a register, a hard disk, a removabledisk, and CD-ROM.

The storage medium is connected to the processor so that the processorcan write and read information into and from the storage medium. Such astorage medium may also be accumulated in the processor. The storagemedium and processor may be arranged in ASIC. Such the ASIC may bearranged in the mobile station UE, the radio base station DeNB or therelay node RN. Further, such a storage medium or a processor may bearranged, as a discrete component, in the mobile station UE, the radiobase station DeNB or the relay node RN.

Thus, the present invention has been explained in detail by using theabove-described embodiments; however, it is obvious that for personsskilled in the art, the present invention is not limited to theembodiments explained herein. The present invention can be implementedas a corrected and modified mode without departing from the gist and thescope of the present invention defined by the claims. Therefore, thedescription of the specification is intended for explaining the exampleonly and does not impose any limited meaning to the present invention.

INDUSTRIAL APPLICABILITY

As described above, in accordance with the present invention, it ispossible to provide a mobile communication system and a radio basestation, by which it is possible for a relay node to reliably receivebroadcast information transmitted by a radio base station.

REFERENCE SIGNS LIST

-   -   DeNB . . . radio base station    -   1 . . . broadcast information transmission unit    -   2 . . . individual signaling unit    -   11 . . . mobile station-use SI transmission unit    -   12 . . . relay node-use SI transmission unit    -   RN . . . relay node    -   21 . . . reception unit    -   22 . . . transmission unit

The invention claimed is:
 1. A radio base station in a mobilecommunication system, in which the radio base station and a relay nodeare connected to each other via a Un interface, and in which the relaynode and a mobile station are connected to each other via a Uuinterface, the radio base station comprising: a broadcast informationtransmission unit configured to transmit system information in asubordinate cell, the system information comprising BCCH (BroadcastControl Channel)-RNTI (Radio Network Temporary Identity) and ascheduling signal via PDCCH (Physical Downlink Control Channel), and anindividual signaling unit configured to transmit the system informationcomprising the RNTI individually assigned to the relay node RN and thescheduling signal via the PDCCH to the relay node via individualsignaling.